A projectile, or shot, capable of enclosing passengers and being safely hurled to the moon by an enormous cannon.

A great cannon having been cast and placed in the soil of Florida, what sort of projectile could be used to send several intrepid passengers to the Moon?

The projectile had now to be filled to the depth of three feet
with a bed of water, intended to support a water-tight wooden
disc, which worked easily within the walls of the projectile.
It was upon this kind of raft that the travelers were to take
their place. This body of water was divided by horizontal
partitions, which the shock of the departure would have to break
in succession. Then each sheet of the water, from the lowest
to the highest, running off into escape tubes toward the top of
the projectile, constituted a kind of spring; and the wooden
disc, supplied with extremely powerful plugs, could not strike
the lowest plate except after breaking successively the
different partitions. Undoubtedly the travelers would still
have to encounter a violent recoil after the complete escapement
of the water; but the first shock would be almost entirely
destroyed by this powerful spring. The upper parts of the walls
were lined with a thick padding of leather, fastened upon springs
of the best steel, behind which the escape tubes were completely
concealed; thus all imaginable precautions had been taken for
averting the first shock; and if they did get crushed, they
must, as Michel Ardan said, be made of very bad materials.

The entrance into this metallic tower was by a narrow aperture
contrived in the wall of the cone. This was hermetically closed
by a plate of aluminum, fastened internally by powerful
screw-pressure. The travelers could therefore quit their prison
at pleasure, as soon as they should reach the moon.

Light and view were given by means of four thick lenticular
glass scuttles, two pierced in the circular wall itself, the
third in the bottom, the fourth in the top. These scuttles then
were protected against the shock of departure by plates let into
solid grooves, which could easily be opened outward by
unscrewing them from the inside. Reservoirs firmly fixed
contained water and the necessary provisions; and fire
and light were procurable by means of gas, contained in a
special reservoir under a pressure of several atmospheres.
They had only to turn a tap, and for six hours the gas would
light and warm this comfortable vehicle.
There now remained only the question of air; for allowing for
the consumption of air by Barbicane, his two companions, and two
dogs which he proposed taking with him, it was necessary to
renew the air of the projectile. Now air consists principally
of twenty-one parts of oxygen and seventy-nine of nitrogen.
The lungs absorb the oxygen, which is indispensable for the support
of life, and reject the nitrogen. The air expired loses nearly
five per cent. of the former and contains nearly an equal volume
of carbonic acid, produced by the combustion of the elements of
the blood. In an air-tight enclosure, then, after a certain
time, all the oxygen of the air will be replaced by the carbonic
acid-- a gas fatal to life. There were two things to be done
then-- first, to replace the absorbed oxygen; secondly, to
destroy the expired carbonic acid; both easy enough to do, by
means of chlorate of potassium and caustic potash.

That, and the few comforts required by gentlemen, are all that are needed!

The first truly scientific work on space flight was not published until Konstantin Ziolkovsky (Tsiolkovsky) published his seminal paper "Exploration of Space With Reactive Devices" in 1903. He showed how a rocket ship could be used to send humans beyond Earth orbit, and included calculations that led him to believe that multiple-staged vehicles would increase the payload (the Chinese had experimented with this idea earlier). NASA paid to translate all of his works into English in 1965.